Method of preparing a carbamate- or urea-functional compound

ABSTRACT

A method of preparing a carbamate or urea-functional compound is described comprising the step of reacting a lactone or hydroxy carboxylic acid with a compound (A) comprising a carbamate or urea group or a group that can be converted to a carbamate or urea group, and an active hydrogen group capable of reacting with the hydroxy carboxylic acid or in a ring-opening reaction with a lactone. The compound thus prepared is useful in curable compositions.

This application is a divisional application of Ser. No. 08/698,525,filed on Aug. 15, 1996, now U.S. Pat. No. 6,498,266.

FIELD OF THE INVENTION

This invention relates to methods of preparing compounds, particularlycarbamate- or urea-functional compounds, particularly compounds usefulin curable compositions such as coating compositions.

BACKGROUND OF THE INVENTION

Carbamate- or urea-functional compositions have been described for usessuch as curable compositions, particularly curable coating compositions.They are often used for topcoats in the automotive and industrialcoatings industry. Color-plus-clear composite coatings are particularlyuseful as topcoats where exceptional gloss, depth of color, distinctnessof image, or special metallic effects are desired. The automotiveindustry has made extensive use of these coatings for automotive bodypanels. Color-plus-clear composite coatings, however, require anextremely high degree of clarity in the clearcoat to achieve the desiredvisual effect. High-gloss coatings also require a low degree of visualaberations at the surface of the coating in order to achieve the desiredvisual effect such as high distinctness of image (DOI).

Such coatings are especially susceptible to a phenomenon known asenvironmental etch. Environmental etch manifests itself as spots ormarks on or in the finish of the coating that often cannot be rubbedout.

Curable coating compositions based on curable components havingcarbamate or urea functionality have been proposed have been describedin the art to provide etch-resistant coatings, e.g., U.S. Pat. No.5,356,669 and WO 94/10211.

In addition to resistance to environmental etch, a number of othercharacteristics can be desireable. For example, it may be desireable toprovide a coating having a high degree of flexibility. This can beparticularly advantageous if the substrate on which the coating isplaced is itself flexible, as in the case of plastic, leather, ortextile substrates.

It is also desirable to reduce the amount of solvent required in coatingcompositions in order to reduce the volatile organic content (VOC),which is better for the environment.

Finally, it is desirable to provide options of different types ofcarbamate- or urea-functional materials to provide coatings with a goodcombination of properties such as durability, hardness, and resistanceto scratching, marring, solvents, and acids.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a method ofpreparing carbamate- or urea-functional compounds capable of providingone or more of the above-described properties. This method comprises amethod of making a carbamate- or urea-functional ester-containingcompound comprising the step of reacting a lactone or hydroxy carboxylicacid with a compound (A) comprising a carbamate or urea group or a groupthat can be converted to a carbamate or urea group, and an activehydrogen group capable of reacting with the hydroxy carboxylic acid orin a ring-opening reaction with a lactone.

Compounds prepared according to the present invention can providecoatings having a good combination of properties such as durability,hardness, and resistance to scratching, marring, solvents, and acids.Such coating compositions can also provide low VOC levels, and can beused to prepare coatings having good flexibility for use over flexiblesubstrates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, a compound having carbamate or ureafunctionality is formed by reaction of a compound (A) having carbamateor urea groups or groups that can be converted to carbamate or urea, andan active hydrogen group.

Carbamate groups can generally be characterized by the formula

wherein R is H or alkyl, preferably of 1 to 4 carbon atoms. Preferably,R is H or methyl, and more preferably R is H. Urea groups can generallybe characterized by the formula

wherein R′ and R″ each independently represents H or alkyl, preferablyof 1 to 4 carbon atoms, or R′ and R″ may together form a heterocyclicring structure (e.g., where R′ and R″ form an ethylene bridge).

According to the present invention, the carbamate- or urea-functionalcompound can be formed by reacting a lactone or hydroxy carboxylic acidwith a compound (A) having an active hydrogen group capable ofring-opening the lactone or undergoing a condensation reaction with thehydroxy carboxylic acid (e.g., hydroxyl, primary amine, acid) and acarbamate or urea group or a group that can be converted to carbamate orurea. When a compound having an active hydrogen group and a group thatcan be converted to carbamate or urea is used to ring-open the lactoneor react with the hydroxy carboxylic acid, conversion of the group to acarbamate or urea can be accomplished during or after the ring-openingreaction.

Compounds having a carbamate or urea group and an active hydrogen groupare known in the art. Hydroxypropyl carbamate and hydroxyethyl ethyleneurea, for example, are well known and commercially available. Aminocarbamates are described in U.S. Pat. No. 2,842,523. Hydroxyl ureas mayalso be prepared by reacting an oxazolidone with ammonia or a primaryamine or by reacting ethylene oxide with ammonia to form an aminoalcohol and then reacting the amine group of that compound or any otheramino alcohol with hydrochloric acid, then urea to form a hydroxy urea.Amino ureas can be prepared, for example, by reacting a ketone with adiamine having one amine group protected from reaction (e.g., by sterichindrance), followed by reaction with HNCO (i.e., the product of thethermal decomposition of urea), and then water. Alternatively, thesecompounds can be prepared by starting with a compound having an activehydrogen and a group that can be converted to carbamate or urea asdescribed below, and then converting that group to the carbamate or ureaprior to commencement of the reaction with the lactone or hydroxycarboxylic acid.

Groups that can be converted to carbamate include cyclic carbonategroups, epoxy groups, and unsaturated bonds. Cyclic carbonate groups canbe converted to carbamate groups by reaction with ammonia or a primaryamine, which ring-opens the cyclic carbonate to form a β-hydroxycarbamate. Epoxy groups can be converted to carbamate groups by firstconverting to a cyclic carbonate group by reaction with CO₂. This can bedone at any pressure from atmospheric up to supercritical CO₂ pressures,but is preferably under elevated pressure (e.g., 60–150 psi). Thetemperature for this reaction is preferably 60–150° C. Useful catalystsinclude any that activate an oxirane ring, such as tertiary amine orquaternary salts (e.g., tetramethyl ammonium bromide), combinations ofcomplex organotin halides and alkyl phosphonium halides (e.g.,(CH₃)₃SnI, Bu₄SnI, Bu₄PI, and (CH₃)₄PI), potassium salts (e.g., K₂CO₃,KI) preferably in combination with crown ethers, tin octoate, calciumoctoate, and the like. The cyclic carbonate group can then be convertedto a carbamate group as described above. Any unsaturated bond can beconverted to carbamate groups by first reacting with peroxide to convertto an epoxy group, then with CO₂ to form a cyclic carbonate, and thenwith ammonia or a primary amine to form the carbamate.

Other groups, such as hydroxyl groups or isocyanate groups can also beconverted to carbamate groups to form a compound (A). However, if suchgroups were to be present on the compound (A) and then converted tocarbamate after reaction with the lactone or hydroxy carboxylic acid,they would have to be blocked so that they would not react with thelactone or hydroxy carboxylic acid or with active hydrogen groups thatare present. When blocking these groups is not feasible, the conversionto carbamate or urea would have to be completed prior to the reactionwith the lactone or hydroxy carboxylic acid. Hydroxyl groups can beconverted to carbamate groups by reaction with a monoisocyanate (e.g.,methyl isocyanate) to form a secondary carbamate group or with cyanicacid (which may be formed in situ by thermal decomposition of urea) toform a primary carbamate group (i.e., unsubstituted carbamates). Thisreaction preferably occurs in the presence of a catalyst as is known inthe art. A hydroxyl group can also be reacted with phosgene and thenammonia to form a compound having primary carbamate group(s), or byreaction of a hydroxyl with phosgene and then a primary amine to form acompound having secondary carbamate groups. Another approach is to reactan isocyanate with a compound such as hydroxyalkyl carbamate to form acarbamate-capped isocyanate derivative. For example, one isocyanategroup on toluene diisocyanate can be reacted with hydroxypropylcarbamate, followed by reaction of the other isocyanate group with anexcess of polyol to form a hydroxy carbamate. Finally, carbamates can beprepared by a transesterification approach where hydroxyl group reactedwith an alkyl carbamate (e.g., methyl carbamate, ethyl carbamate, butylcarbamate) to form a primary carbamate group-containing compound. Thisreaction is performed under heat, preferably in the presence of acatalyst such as an organometallic catalyst (e.g., dibutyltindilaurate). Other techniques for preparing carbamates are also known inthe art and are described, for example, in P. Adams & F. Baron, “Estersof Carbamic Acid”, Chemical Review, v. 65, 1965.

Groups such as oxazolidone can also be converted to urea after reactionwith the lactone or hydroxy carboxylic acid. For example, hydroxyethyloxazolidone can be used to initiate the reaction with the lactone orhydroxy carboxylic acid, followed by reaction of ammonia or a primaryamine with the oxazolidone to generate the urea functional group.

Other groups, such as amino groups or isocyanate groups can also beconverted to urea groups to form a compound (A). However, if such groupswere to be present on the compound (A) and then converted to urea afterreaction with the lactone or hydroxy carboxylic acid, they would have tobe blocked so that they would not react with the lactone, the hydroxycarboxylic acid, or with the active hydrogen groups. When blocking thesegroups is not feasible, the conversion to carbamate or urea would haveto be completed prior to reaction with the lactone or hydroxy carboxylicacid. Amino groups can be converted to urea groups by reaction with amonoisocyanate (e.g., methyl isocyanate) to form a secondary urea groupor with cyanic acid (which may be formed in situ by thermaldecomposition of urea) to form a primary urea group. This reactionpreferably occurs in the presence of a catalyst as is known in the art.An amino group can also be reacted with phosgene and then ammonia toform a compound having primary urea group(s), or by reaction of an aminogroup with phosgene and then a primary amine to form a compound havingsecondary urea groups. Another approach is to react an isocyanate with ahydroxy urea compound to form a urea-capped isocyanate derivative. Forexample, one isocyanate group on toluene diisocyanate can be reactedwith hydroxyethyl ethylene urea, followed by reaction of the otherisocyanate group with an excess of polyol to form a hydroxy carbamate.

One preferred class of compounds having an active hydrogen group and agroup that can be converted to carbamate is the hydroxyalkyl cycliccarbonates. Hydroxyalkyl cyclic carbonates can be prepared by a numberof approaches. Certain hydroxyalkyl cyclic carbonates like3-hydroxypropyl carbonate (i.e., glycerine carbonate) are commerciallyavailable. Cyclic carbonate compounds can be synthesized by any ofseveral different approaches. One approach involves reacting an epoxygroup-containing compound with CO₂, under conditions and with catalystsas described hereinabove. Useful catalysts include any that activate anoxirane ring, such as tertiary amine quaternay salts (e.g., tetramethylammonium bromide), tin and/or phosphorus complex salts (e.g., (CH₃)₃SnI,(CH₃)₄PI). Epoxides can also be reacted with β-butyrolactone in thepresence of such catalysts. In another approach, a glycol like glycerineis reacted at temperatures of at least 80° C. with diethyl carbonate inthe presence of a catalyst (e.g., potassium carbonate) to form ahydroxyalkyl carbonate. Alternatively, a functional compound containinga ketal of a 1,2-diol having the structure:

can be ring-opened with water at temperatures of at least 60° C.,preferably with a trace amount of acid, to form a 1,2-glycol, which isthen further reacted with diethyl carbonate to form the cycliccarbonate.

Cyclic carbonates typically have 5–6-membered rings, as is known in theart. Five-membered rings are preferred, due to their ease of synthesisand greater degree of commercial availability. Six-membered rings can besynthesized by reacting phosgene with 1,3-propane diol under conditionsknown in the art for the formation of cyclic carbonates. Preferredhydroxyalkyl cyclic carbonates used in the practice can be representedby the formula:

where R (or each instance of R if n is more than 1) is a hydroxyalkylgroup of 1–18 carbon atoms, preferably 1–6 carbon atoms, and morepreferably 1–3 carbon atoms, which may be linear or branched and mayhave subsituents in addition to the hydroxyl (which itself may beprimary, secondary, or tertiary), and n is 1 or 2, which may besubstituted by one or more other substituents such as blocked amines orunsaturated groups. More preferably, R is —C_(m)H_(2m)OH where thehydroxyl may be primary or secondary and m is 1 to 8, and even morepreferably, R is —(CH₂)_(p)—OH where the hydroxyl is primary and p is 1to 2.

Lactones that can be ring opened by an active hydrogen are well-known inthe art. They include, for example, ε-caprolactone, γ-caprolactone,β-butyrolactone, β-propriolactone, γ-butyrolactone,α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone,δ-valerolactone, γ-nonanoic lactone, γ-octanoic lactone, andpentolactone. In one preferred embodiment, the lactone isε-caprolactone. Lactones useful in the practice of the invention canalso be characterized by the formula:

wherein n is a positive integer of 1 to 7 and R is one or more H atoms,or substituted or unsubstituted alkyl groups of 1–7 carbon atoms.

The lactone ring-opening reaction is typically conducted under elevatedtemperature (e.g., 80–150° C.). The reactants are usually liquids so asolvent is not necessary. However, a solvent may be useful in promotinggood conditions for the reaction even if the reactants are liquid. Anynon-reactive solvent may be used, including both polar and nonpolarorganic solvents. Examples of useful solvents include toluene, xylene,methyl ethyl ketone, methyl isobutyl ketone, and the like. A catalyst ispreferably present. Useful catalysts include proton acids (e.g.,octanoic acid, Amberlyst® 15 (Rohm & Haas)), and tin catalysts (e.g.,stannous octoate). Alternatively, the reaction can be initiated byforming a sodium salt of the hydroxyl group on the molecules to reactwith the lactone ring.

The lactone ring-opening reaction provides chain extension of themolecule if sufficient amounts of the lactone are present. The relativeamounts of the carbamate or urea compound (A) and the lactone can bevaried to control the degree of chain extension. The opening of thelactone ring with a hydroxyl or amine group results in the formation ofan ester or amide and an OH group. The OH group can then react withanother available lactone ring, thus resulting in chain extension. Thereaction is thus controlled by the proportion of lactone in the relativeto the amount of initiator compound (A). In the practice of the presentinvention, the ratio of equivalents of lactone to equivalents of activehydrogen groups on (A) is preferably from 0.1:1 to 10:1, and morepreferably from 1:1 to 5:1. When the lactone is opened with with anacid, the resulting compound has an acid group, which can then beconverted to a hydroxyl group by well-known techniques such as reactionwith ethylene oxide.

A compound (A)(1) having a hydroxyl active hydrogen group can also bereacted with a hydroxy carboxylic acid to form the carbamate- orurea-functional compound (A). Useful hydroxy carboxylic acids includedimethylhydroxypropionic acid, hydroxy stearic acid, tartaric acid,lactic acid, 2-hydroxyethyl benzoic acid, and N-(2-hydroxyethyl)ethylenediamine triacetic acid. The reaction can be conducted under typicaltransesterification conditions, e.g., temperatures from room temperatureto 150° C. with transesterification catalysts such as such as calciumoctoate, metal hydroxides (e.g., KOH), Group I or II metals (e.g., Na,Li), metal carbonates (e.g., K₂CO₃) which may be enhanced by use incombination with crown ethers, metal oxides (e.g., dibutyltin oxide),metal alkoxides (e.g., NaOCH₃, Al(OC₃H₇)₃), metal esters (e.g., stannousoctoate, calcium octoate, or protic acids (e.g., H₂SO₄), MgCO₃, orPh₄SbI. The reaction may also be conducted at room temperature with apolymer-supported catalyst such as Amberlyst-15® (Rohm & Haas) asdescribed by R. Anand, Synthetic Communications, 24(19), 2743–47 (1994),the disclosure of which is incorporated herein by reference.

In one embodiment of the invention, after the reaction of compound (A)with the lactone or hydroxy carboxylic acid is complete, the reactionproduct (hereinafter referred to as (A)(1) may be further reacted with acompound (A)(2) that is reactive with the hydroxyl groups on a pluralityof molecules of (A)(1), but that is not reactive with the carbamate orurea groups thereon. Thus, in the final product produced by thisreaction, the residue of compound (A)(2) can be described as a core towhich a plurality of carbamate- or urea-functional residues of compound(A)(1) are attached. It is also contemplated that compound (A)(1) may beadmixed with other compounds comprising a hydroxyl group plus acarbamate or urea group (e.g., hydroxypropyl carbamate) prior to thereaction with compound (A)(2). In such a case, the resulting reactionproduct mixture will reflect the stoichiometric ratio of compound (A)(1)to such other compounds.

Compounds that are useful as (A)(2) include polyisocyanates, dialkylcarbonates, cyclic carbonates, CO₂, phosgene, acetals, cyclic or linearphosphazene-based compounds, substituted or unsubstituted cyclicsiloxanes or silanes, or substituted or unsubstituted linear siloxanesor silanes, which may be described by the formula SiX_(m)R_(n) where Xis a group that is reactive with protons, such as a halide, alkoxy,hydride, or acetate, R is a group that is non-reactive with protons suchas alkyl, silane, or siloxane, m=2–4, and m+n=4, SO₂ sources such as SO₃or SO₂Cl₂, POCl₃, POCl₂R where R is alkyl or aryl. With certain of thecompounds (A)(2), a diol may also be included in the reaction mixturecomprising (A)(1) and (A)(2) to obtain chain extension with carbamate orurea termination. This can be done, for example, with phosgene where thephosgene/diol reaction results in chain extension and the reaction ofphosgene with compound (A)(1) results in chain termination with acarbamate or urea group.

The polyisocyanate can be an aliphatic polyisocyanate, including acycloaliphatic polyisocyanate or an aromatic polyisocyanate. Usefulaliphatic polyisocyanates include aliphatic diisocyanates such asethylene diisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane,1,6-diisocyanatohexane, 1,4-butylene diisocyanate, lysine diisocyanate,1,4-methylene bis-(cyclohexyl isocyanate) and isophorone diisocyanate.Useful aromatic diisocyanates and araliphatic diisocyanates include thevarious isomers of toluene diisocyanate, meta-xylylenediioscyanate andpara-xylylenediisocyanate, also 4-chloro-1,3-phenylene diisocyanate,1,5-tetrahydro-naphthalene diisocyanate, 4,4′-dibenzyl diisocyanate and1,2,4-benzene triisocyanate can be used. In addition, the variousisomers of α,α,α′,α′-tetramethyl xylylene diisocyanate can be used.Oligomeric or polymeric polyisocyanates prepared by reaction of anexcess of monomeric polyisocyanates with a polyol may be used. Also,isocyanurates such as the isocyanurate of isophorone diisocyanate or theisocyanurate of hexamethylene diisocyanate may be used. Biurets ofisocyanates such as DESMODUR® N100 from Mobay may also be useful.

Dialkyl carbonates, cyclic carbonates, CO₂, diphenyl carbonates, orphosgene may be used as compound (A)(2) to react with and link two(A)(1) compounds via a carbonate linking group. When phosgene is used,phosgene may be added to a solution of compound (A)(1) at a molar ratioof about 1 mole phosgene to 2 moles (A)(1) (or 2 moles (A)(1) plus otherhydroxy carbamate or urea compounds such as hydroxypropyl carbamate).This reaction may be conducted at temperatures of less than 7° C. orunder pressure in order to maintain phosgene in it's liquid state, oralternatively, gaseous phosgene may be bubbled through the system. Asalting base (e.g., NaOH) may be used to help drive the reaction. Thereaction may be conducted in virtually any aprotic solvent attemperatures of −20° C. to 80° C. and pressures of atmospheric to 40psi.

Cyclic carbonates or dialkyl carbonates may be used as compound (A)(2)to react with compound (A)(1) by heating (e.g., 80–200° C.) theappropriate molar mixture (2 moles (A)(1) plus any other hydroxycarbamate or urea and 1 mole cyclic carbonate or dialkyl carbonate) witha transesterification catalyst such as calcium octoate. Useful dialkylcarbonates include diethyl carbonate, dimethyl carbonate, dipropylcarbonate, diphenyl carbonate, and dibutyl carbonate. Useful cycliccarbonates include propylene carbonate, glycerine carbonate, anddimethyl ethylene carbonate. Cyclic carbonates may also be formed fromany unsaturated bond by reaction of the unsaturated bond with peroxideto form an oxirane ring, followed by reaction with CO₂ to form thecyclic carbonate. Useful catalysts include metal hydroxides (e.g., KOH),Group I or II metals (e.g., Na, Li), metal carbonates (e.g., K₂CO₃)which may be enhanced by use in combination with crown ethers, metaloxides (e.g., dibutyltin oxide), metal alkoxides (e.g., NaOCH₃,Al(OC₃H₇)₃), metal esters (e.g., stannous octoate, calcium octoate), orprotic acids (e.g., H₂SO₄), MgCO₃, or Ph₄SbI. Any solvents used shouldbe inert to transesterification. The catalysts and/or reactionconditions may need to be adjusted to minimize transesterification ofthe ester groups from the ring-opened lactone in compound (A)(1). CO₂may also be used as compound (A)(2) under similar conditions withsimilar catalysts plus it may be used at pressures of 1 to 40 atm.

Compounds having inorganic reactive groups may also be used to reactwith the hydroxyl groups of compound (A)(1). These include phosphoruscompounds such as POCl₃ or hexachlorocyclotriphosphazene, SO₂ sourcessuch as SO₃ or SO₂Cl₂ or silane-based systems such as substituted orunsubstituted cyclic siloxanes or silanes, or substituted orunsubstituted linear siloxanes or silanes, which may be described by theformula SiX_(m)R_(n) where X is a group that is reactive with protons,such as a halide, alkoxy, hydride, or acetate, R is a group that isnon-reactive with protons such as alkyl, silane, or siloxane, m=2–4, andm+n=4.

Phosphazene-based compounds (e.g., hexachlorocyclotriphosphazene) orPOCl₃ may be used as compound (A)(2) to react with (A)(1). In a typicalreaction, one equivalent (based on chlorine content) of the phosphorusreagent is dissolved in a dry ether solvent such as diethyl ether oftetrahydrofuran to form a solution of approximately 50%. 1.5 equivalentsof sodium hydride are added followed by one equivalent of (A)(1) (or(A)(1) plus other hydroxy carbamate or urea compounds). The mixture isallowed to exotherm to the reflux temperature of the solvent, with thereaction temperature controlled by the addition rate of the (A)(1)compound. After addition of the (A)(1) compound is complete, thereaction mixture is heated to reflux and held for 2–3 hours. The mixtureis then cooled, filtered to remove sodium chloride and any unreactedsodium hydride, and the solvent removed under vacuum.

Silane-based compounds may also be used as compound (A)(2). Suchcompounds may be described by the formula SiX_(m)R_(n) where X is agroup that is reactive with protons, such as a halide, alkoxy, hydride,or acetate, R is a group that is non-reactive with protons such asalkyl, silane, or siloxane, m=2–4, and m+n=4. These compounds may reactwith (A)(1) in any dry aprotic solvent (e.g., tetrahydrofuran) underconditions known in the art, which may depend on the nature of the Xgroup. When X is a hydride, the reaction is preferably begun withchilled reactants (e.g., 0° C.) under an inert atmosphere usingcatalysts such as tin catalysts. After the addition of materials iscomplete, amd dry methanol is added to react with any free remainingSi—H bonds. If X is a halide, the reaction is preferably begun under aninert atmosphere at room temperature. The mixture is then heated toreflux to drive the reaction to completion. HCl is given off as aby-product. If X is alkoxy, the reaction is preferably begun under aninert atmosphere at room temperature, which may be maintained for theduration of the reaction. A molecular sieve may be used to absorb thealcohol side product that is formed. Slightly basic or acidic pH willaccelerate this reaction; however, it will also accelerate the formationof Si—O—Si bonds.

For SO₂ sources, the SO₃ can be reacted with the (A)(1) by bubbling SO₃through the (A)(1) compound if it is in liquid form or by dissolving(A)(1) in a solvent and then bubbling SO₃ through the solution. Thereaction of SO₂Cl₂ with (A)(1) may be assisted by the pre-reaction of(A)(1) with Na or NaOR (where R is an organic radical).

In another embodiment of the invention, after the reaction to formcompound (A)(1) is complete, (A)(1) may be reacted with a component(A)(3) that is reactive with compound (A)(1) to convert a hydroxyl groupon compound (A)(1) to a carbamate group, or a component comprising agroup that is reactive with a hydroxyl group on compound (A)(1) and acarbamate or urea group or group that can be converted to carbamate orurea.

A number of compounds may be used as compound (A)(3) to convert ahydroxyl group on compound (A)(1) to a carbamate group. Hydroxyl groupscan be converted to carbamate groups by reaction with a monoisocyanate(e.g., methyl isocyanate) to form a secondary carbamate group or withcyanic acid (which may be formed by the thermal decomposition of urea)to form a primary carbamate group (i.e., unsubstituted carbamates). Thisreaction is performed preferably in the presence of a catalyst as isknown in the art. A hydroxyl group can also be reacted with phosgene andthen ammonia to form a compound having primary carbamate group(s), or byreaction of a hydroxyl with phosgene and then a primary amine to form acompound having secondary carbamate groups.

Various compounds can be used as compound (A)(3) that have a group thatis reactive with the hydroxyl group on (A)(1) and a carbamate or ureagroup or a group that can be converted to carbamate or urea. Alkylcarbamates (e.g., methyl carbamate, butyl carbamate) or substitutedalkyl carbamates (e.g., hydroxypropyl carbamate) can be transesterifiedwith the hydroxyl group on compound (A)(1). This reaction is performedunder heat, preferably in the presence of a catalyst such as anorganometallic catalyst (e.g., dibutyltin dilaurate). A methylolacrylamide can be reacted with the hydroxyl group on (A)(1) and thenconverted to carbamate. In this reaction, the unsaturated bond is thenreacted with peroxide, CO₂, and ammonia as described above. The epoxygroups are then reacted with CO₂ to form cyclic carbonate groups, whichare converted to carbamate groups by reaction with ammonia.Partially-blocked toluene diisocyanate can also be used as compound(A)(3). In one embodiment, the unblocked isocyanate on thepartially-blocked toluene diisocyanate can be reacted with the hydroxylgroup on (A)(1). The other isocyanate can then be unblocked and reactedwith a hydroxyalkyl carbamate (e.g., hydroxypropyl carbamate) or ahydroxy urea (e.g., hydroxyethyl ethylene urea). Alternatively, theunblocked isocyanate can be reacted with a hydroxyalkyl carbamate (e.g.,hydroxypropyl carbamate) or a hydroxy urea (e.g., hydroxyethyl ethyleneurea), followed by unblocking of the other isocyanate group and reactionwith the hydroxyl group on compound (A)(1). Other polyisocyanates can beused to append carbamate or urea groups onto the hydroxyl group on(A)(1), but they will result in competing side reactions where thepolyisocyanate reacts with more than one (A)(1) molecule or more thanone hydroxyalkyl carbamate or hydroxy urea.

Carbamate- or urea-functional compounds prepared according to thepresent invention may be used in curable compositions such as curablecoating compositions, and cured by reaction with a component (B) that isa compound having a plurality of functional groups that are reactivewith the carbamate or urea groups. Such reactive groups include activemethylol or methylalkoxy groups on aminoplast crosslinking agents or onother compounds such as phenol/formaldehyde adducts, siloxane or silanegroups, and anhydride groups. Examples of (B) compounds include melamineformaldehyde resin (including monomeric or polymeric melamine resin andpartially or fully alkylated melamine resin), urea resins (e.g.,methylol ureas such as urea formaldehyde resin, alkoxy ureas such asbutylated urea formaldehyde resin), N-methylol acrylamide emulsions,isobutoxy methyl acrylamide emulsions, polyanhydrides (e.g.,polysuccinic anhydride), and siloxanes or silanes (e.g.,dimethyldimethoxy silane). Aminoplast resin such as melamineformaldehyde resin or urea formaldehyde resin are especially preferred.Also preferred are aminoplast resins where one or more of the aminonitrogens is substituted with a carbamate group for use in a processwith a curing temperature below 150° C., as described in U.S. Pat. No.5,300,328.

Other aspects regarding the use in curable coating compositions ofcompounds prepared according to the invention are described in copendingU.S. patent application entitled “Curable Coating Composition”, filed oneven date herewith in the names of Brian Bammel, John McGee, WalterOhrbom, Todd Seaver, Paul Harris, and John Rehfuss, the disclosure ofwhich is incorporated herein by reference.

The invention is further described in the following examples.

Preparation 1

A clean 5-liter three-necked round bottomed flask was equipped with anagitator, condenser, thermocouple, and nitrogen line. To this apparatuswas added 1735.0 g ε-caprolactone, 761.9 g hydroxypropyl carbamate, 234g xylene, and 4.4 g stannous octoate. The mixtured was stirred undernitrogen atmosphere and heated to a temperature of 130° C. Temperaturewas maintained for a period of 6 hours to complete the synthesis, andthen cooled.

EXAMPLE 1 Coating Composition

A clearcoat composition was prepared by mixing 1000 g of Preparation 1,337.4 g monomeric fully metholated melamine, and 6.1 g dodecylbenzylsulfonic acid.

This composition was spray-applied to a variety of substrates using aconventional air atomization siphon gun. Both rigid and flexiblesubstrates were coated. A portion of the panels were applied wet on wetover conventional high solids basecoat. For these systems, the basecoat(an industry standard high-solids OH acrylic/melamine system) wasapplied, followed by a 10-minute ambient flash, at which point theabove-described coating composition was applied. After an additional 5minutes ambient flash, the panels were baked at 250° F. for 30 minutes.

The coating composition of the Example resulted in a contiguous curedhard clear film. The measured VOC of the clearcoat mixture was found tobe 1.2 lbs/gal.

Preparation 2

A clean 12-liter three-necked round bottomed flask was equipped with anagitator, condenser, thermocouple, and nitrogen line. To this apparatuswere added 6033 g ε-caprolactone, 2516 g hydroxypropyl carbamate, 450 gtoluene, and 15 g stannous octoate. The mixtured was stirred undernitrogen atmosphere and heated to a temperature of 130° C. Temperaturewas maintained for

Preparation 3

2092 g of the component prepared according to Preparation 2, 412 g1,6-hexamethylene diisocyanate was added under nitrogen atmosphere to a5-liter three-necked round bottomed flask was equipped with an agitator,condenser, thermocouple, and nitrogen line. The mixture was slowlyheated to 60° C. at which point the mixture exothermed. The mixture wascooled such that a maximum exotherm temperature of 99° C. was reached,after which a batch temperature of 86° C. was maintained for a period of4.25 hours. The mixture was cooled and diluted with 286.7 g n-butylacetate.

EXAMPLE 2

A clearcoat was prepared by mixing 166 g of the material preparedaccording to Preparation 3, 33.7 g monomeric fully methylated melamine,5.22 g of a solution of blocked dodecylbenzyl sulfonic acid (25%active), 5.22 g Tinuvin® 1130, 0.87 g polyacrylate additive solution,1.45 g surface modifier additive solution, 4.25 g n-butyl acetate and42.5 g ethylene glycol butyl ether acetate.

The coating composition was spray-applied to a variety of substratesusing a conventional air atomization siphon gun. Both rigid and flexiblesubstrates were coated. A portion of the panels were applied wet on wetover conventional high solids basecoat. For these systems, the basecoat(an industry standard high-solids OH acrylic/melamine system) wasapplied, followed by a 10 minute 200° F. flash. After cooling, thecoating mixture was applied directly to the basecoat. After anadditional 15 minutes ambient flash, the panels were baked at 250° F.for 30 minutes.

The coating composition of the Example resulted in a contiguous curedhard clear film. The measured VOC of the clearcoat mixture was found tobe 3.07 lbs/gal.

Preparation 4

A three-necked 1-liter flask was equipped with an agitator,thermocouple, nitrogen line, and condenser. To the flask were added 59.5parts Hydroxypropyl carbamate, 171.2 parts ε-caprolactone, 98.8 partsxylene, and 0.4 parts stannous octoate under nitrogen atmosphere. Themixture was heated to 130° C. for a period of 10 hours, at which point0.2 parts additional stannous octoate were added. The mixture was heatedto 145° C. for a period of 1 hour and cooled.

Preparation 5

A three-necked 1-liter flask was equipped with agitator in the centerneck, a thermocouple and nitrogen line in one neck and a trap in thethird to condense and collect volatiles with a mixture of dry ice andisopropanol.

125.0 parts of Preparation 4, 11.2 parts diethyl carbonate, and 4.0parts dibutyltin dimethoxide were added to the flask under nitrogenatmosphere. Heat was applied such that temperature was maintained around100° C. for three hours during which time volatiles were collected inthe trap. Recovered ethanol as well as diethyl carbonate distilled totrap were monitored by gas chromatograph. Periodically, additions ofdiethyl carbonate were made to the flask to replenish loss to the trap.The mixture was heated for an additional period of 10.5 hours attemperatures ranging from 90–132° C. with continued monitoring ofrecovered ethanol and replenishment of diethyl carbonate as needed.

The resulting resin was reduced with 29.8 parts amyl acetate.

EXAMPLE 3

A clearcoat was prepared by combining 10 parts Preparation 5, 2 partsResimene® 747, 1.8 parts Solvesso® Aromatic 100 solvent mixture, and0.48 parts docecylbenzylsulfonic acid. Once homogenious, the mixture wasdrawn over a glass plate, and cured at 250° F. for 30 minutes. Theresult was a tough, flexible, solvent-resistant coating.

Preparation 6

In a three necked three liter flask equipped with an agitator,thermocouple, nitrogen line, and condenser, were added 841.5 ghydroxypropyl carbamate, 806.9 g ε-caprolactone, and 2.8 g stannousoctoate under nitrgen atmosphere. The mixture was heated to atemperature of 130° C. for a period of 5.5 hours and then cooled to roomtemperature.

Preparation 7

To 200 parts of Preparation 6 was added 102.7 parts of urea, and 1.6parts of diethylene triamine. The system was heated to 130° C. and heldfor 1 hour. The system was then heated to 140° C. for 5.5 hours. Thisresulted in the formation of cyanic acid from the thermal decompositionof the urea, which reacted with the hydroxyl groups on the Preparation 1compound form carbamate groups. The resulting solid product was washedwith ethyl acetate, disolved in methylene chloride, and filtered. Themethylene chloride was then removed by evaporation to yield the finalproduct.

EXAMPLE 4

The following components were mixed and drawn down on glass substrate toform an 8 mm-thick layer:

6.2 g Preparation 7 1.7 g Resimene ® 747 melamine resin 0.04 g dodecylbenzene sulfonic acid  10 g amyl acetate

The coated glass substrate was baked at 250° F. for 30 minutes,resulting in a clear tack-free film that passed 200 methylethyl ketonedouble rubs with only surface scratches.

The invention has been described in detail with reference to preferredembodiments thereof. It should be understood, however, that variationsand modifications can be made within the spirit and scope of theinvention.

1. A coating composition comprising a carbamate- or urea-functionalester-containing compound, said compound comprising the reaction productof a lactone or hydroxy carboxylic acid with a second compoundcomprising a carbamate or urea group or a group that can be converted toa carbamate or urea group, and an active hydrogen group capable ofreacting with the hydroxycarboxylic acid or in a ring-opening reactionwith a lactone.
 2. A coating according to claim 1 wherein said activehydrogen group on said second compound is a hydroxyl group.
 3. A coatingaccording to claim 1 wherein said active hydrogen group on said secondcompound is an amino group.
 4. A coating composition according to claim1 wherein said second compound is a β-hydroxy carbamate that is aproduct of a ring-opened cyclic carbonate.